The general practice in the window shade industry is to manufacture window shades in only broad increments of lengths and have those lengths cut to the specific size required by the consumer at the time of sale. In today's market, the shade material itself is usually cloth or vinyl (plain or reinforced), and the rollers upon which the vinyl shades are wrapped are either convolute cardboard or telescoping metal tubes.
There is only a minimum of standardization of the rollers with regard to size or material, and heretofore there has not been available a machine that is both versatile enough to cut vinyl shades wrapped on either metal or convolute cardboard rollers and simple enough to be safely used by the general public without assistance from store personnel. Most of the in-store shade cutting machines have exposed moving parts and tend to be too complex and dangerous to be safely operated by the general public to operate.
One prior cutting machine employs shielded moving parts and is able to automatically cut vinyl shades relatively safely. However, it is only useable for shades mounted on convolute cardboard rollers, and thus lacks the versatility necessary for widespread general use.
One problem with shielding the moving parts is that it makes it difficult to load and control the machine. The prior art machines have lacked adequate sensing features and controls.
Another attempt to solve the problem is described in U.S. Pat. No. 4,006,770, in which a strippable vinyl shade has vertical score lines in it to allow the consumer to peel away the portion of the shade that is not needed. Such "peel-to-width" shades, however, have the disadvantage that they can employ only unreinforced vinyl film, the score lines tend to promote unwanted rupture, and are noticeable when the shade is rolled up.